--- Process.setpgrp(pid, pgrp)
--- Process.setpgrp               ruby 1.7 feature
--- Process.setpgid(pid, pgrp)

    pid Υץ롼פꤷޤpid  0 λϥ
    ȥץ̣ޤ

    ץ롼פ 0 ֤ޤԤ
    ϡ㳰 Errno::EXXX ȯޤ

    ruby 1.7 feature:
    version 1.7 ǤϡProcess.setpgrp ϡޤ

